Finding the Fourth Proportional to 1,441.20, 1,988.88 and 811.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,441.20 : 1,988.88 = 811.78 : x
2. Step 2: Convert to fraction form
   1,441.20/1,988.88 = 811.78/x
3. Step 3: Cross multiply
   1,441.20x = 1,988.88 × 811.78
4. Step 4: Simplify right side
   1,441.20x = 1,614,533.01
5. Step 5: Solve for x
   x = 1,614,533.01/1,441.20
6. Step 6: Final answer
   x = 1,120.27